GENERAL DESCRIPTION
The SA2531 is a CMOS integrated circuit that contains all the functions needed to form a high performance electronic telephone.
The device incorporates LD/MF repertory dialling, melody generation, ring frequency discrimination and a high quality speech circuit.
A RAM is on chip for a 31 digit last number redial and 14 memories each containing up to 21 digits. The sliding cursor procedure makes Last Number Redial easy behind a PABX.
The SA2531 (exept the SA2531D) incorporates a volume control for the earpiece. The receive volume can be controlled by the VOL key (+4dB) or by the +/- keys (+6dB/-4dB in 5 steps).
The versatility of the circuit is provided by on chip programmability and a few external components. This allows easy adaption to different PTT requirements without changing the PCB of the telephone.

■ Speech circuit, LD/MF Repertory Dialler
and Tone Ringer on one 28 pin CMOS
chip
■ Net 4 compatible
■ Soft clip to avoid harsh distortion
■ Line Loss Compensation selectable by
pin option
■ Power down mode
■ Versatile applications for different PTT
demands
■ 31 digit last number redial
■ Sliding Cursor protocol with comparison
■ 2 Flash keys, 100 ms and 280 ms (option
600 ms)
■ Ring frequency discrimination
FEATURES
■ Operating range from 13 to 100 mA
   (down to 5 mA with reduced performance)
■ Volume control of receive signalExcept "D")
■ Low noise (max. -72dBmp)
■ Real or Complex impedance on chip programmable
■ LD/MF switchable dialling
■ 14 memories, 4 direct/10 indirect or 10 direct
■ Pause key for 2, 3 or 6 sec Auto Pause or Wait function
■ On chip MF filter (CEPT CS 203 compatible)
■ 3-tone melody generator